1. Field of the Invention
The present invention relates to a connection, notably for submarine conduits, as well as to a female connection part intended to be coupled with a complementary male part in order to form such a connection.
2. Brief Description of the Related Art
Generally, a connection is formed with a male part and a female part which may comprise a male connection element and a female connection element respectively. When this occurs under the sea, the fitting of the male element into the female element may result from a mechanical device displacing one of the connection parts towards the other connection part. In this case, it may happen that the male element and the female element are not properly aligned with each other during the fitting operation.
US-2005-0164538 describes a connection, the male and female connection parts of which have long guiding zones in order to compensate a possible lack of alignment during their coupling. Thus, in order to facilitate the guiding of the male connection part into the female connection part, their facing surfaces are complementary. In order to allow fluid to flow between the conduits to be connected, the female element and the male element each include a passage in which the fluid may transit through. When the connection parts are assembled, the distal ends of each of these passages are therefore facing each other. By convention, the terms “proximal” and “distal” are defined by referring to the end of the connection part capable of being connected to a fluid conduit. The term “proximal” therefore designates an object close to the conduit, whereas the term “distal” designates an object which is further away from it.
The distal ends each have a shrinked section on which a valve intended to block the corresponding passage is supported. Thus, the male and female elements each include a translationally mobile valve between a blocking position, where it is supported on the shrinked section of the passage, and an open position where it is retracted inside the corresponding connection element. Further, the male and female elements each comprise an elastic member allowing the corresponding valve to be brought back into its position for blocking the passage.
As shown by US-2005-0164538, the relatively narrow and elongated shape of the external surface of the male element determines the geometry of its valve. Thus, this valve has the shape of an elongated relatively thin rod. The valve fitting out the female element also has the shape of an elongated thin rod. Both of these rods are laid out coaxially, and they are able to push back each other, in translation in their respective passages, after having been put into contact by coupling of the male and female elements.
Within the scope of a submarine application, the connection is subject to an external pressure which depends on the depth at which it is installed. This depth may be very great, such as in the case of offshore platforms. In order to maintain the seal of each connection element before their assembly, the elastic members should then exert large forces on the valves so as to maintain them in the blocking position. In the case illustrated by US-2005-0164538, each elastic restoring member consists of a helical spring, the overall dimensions of which are such that it has to be laid out inside the proximal portion of the passage behind the valve.
Each spring therefore exerts a compression force on the rear portion of the rod of the valve which it maintains in position. Consequently, the rod of each valve has a risk of deformation by buckling, which may lead to failure of the connection. One of the conduits may further contain a fluid under high pressure of the order of 1,200 bars, whereas the other one may contain a liquid which is at a comparatively low pressure, such as the piezometric pressure prevailing at the depth where the connection is found. In this case, the force required for opening the valve which blocks the high pressure conduit has to be very large. Each valve is then subject to considerable axial compression stresses, which are capable of causing its buckling.
The risk of buckling is further worsened by a lack of alignment between the male and female parts, which may occur during their assembly. Now, such a lack of alignment is relatively frequent when the coupling is achieved in a submarine medium by a robot. The risk of buckling also results from the limitation of the diameter of the valve rods with the purpose of obtaining the desired fluid flow rate in the passages.
Moreover, FR-A-1 360 204 describes a female element intended to receive a male connection element. The female element includes a fluid passage housing a spring and a blocking ball, a bore for receiving the male element and a member for actuating the ball capable of sliding in a guiding chamber of the female element. The actuating member comprises two axial rods, so as to open both sections of the conduit simultaneously. The female element has a thread so as to be screwed into the body of a female part. Such a screwed connection requires perfect alignment of the male element and of the female element during their connection otherwise the actuating member has risks of buckling and/or bending, in particular for high fluid pressures.